This invention relates to separating oil from air-oil mixtures, more particularly engine oil from air and other gases and especially separating, in a single unit, air-oil mixtures of differing proportions. An example is an air-oil separator which takes the lubricating oil discharge from a turbocharger and the mist from the crankcase vent and collects the deaerated oil in the separator sump while air and gases are vented. It is obviously advisable to separate the gases from the oil before recirculating the oil.
Prior practice is to feed the turbocharger oil direct to the engine-driven pump without separation or to use two separators. The problem with feeding the oil direct to the pump is that high time engines under idle or low power conditions overtax the pump with blow-by gases from both the engine and the turbocharger. Also, under high power conditions on low time engines the pressure at the pump inlet may exceed the pressure in the crankcase, especially at high altitudes. This causes flooding of the breather separator. The addition of another separator for the turbocharger oil results in deaerating the turbocharger oil but does not solve the breather separator's overflow flooding under high power conditions.
U.S. Pat. Nos. 2,639,779 and 2,925,878 show separators which include two stages of separation but only a single inlet which results in all proportions of gas-liquid mixtures passing through both stages successively. The earlier patent is adapted to air-oil mixtures low in air while the later patent is adapted to mixtures high in air. The elements and purpose in this prior art are different than those in this invention.